Canopus (nuclear test)

Canopus (also Opération Canopus in French) was the code name for France's first two-stage thermonuclear test, conducted on August 24, 1968 at Fangataufa atoll. The test made France the fifth country to test a thermonuclear device after the United States, the Soviet Union, the United Kingdom and China.

In 1966, France was able to use fusion fuel to boost plutonium implosion devices with the Rigel shot. Roger Dautray, a nuclear physicist, was selected by the CEA to lead the development effort to construct a two-stage weapon. France did not have the ability to produce the materials needed for a two-stage thermonuclear device at the time, so 151 tons of heavy water was purchased from Norway and an additional 168 tons from the United States. This heavy water went into nuclear reactors in 1967 to produce tritium needed for the device.

France was to test the new device as part of a 5-shot series conducted at the nuclear testing grounds in French Polynesia. The device weighed three tons and used a lithium deuteride secondary stage with a highly enriched uranium jacket primary.

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